Tokyo, the most populous metropolitan area in the world

The question of which are the world's largest cities is a complex one, to which there is no single correct answer, simply because there are many different ways of defining a "city".

One concept is that of the metropolitan area, which is based on the concept of a labor market area and is typically defined as an employment core (an area with a high density of available jobs) and the surrounding areas that have strong commuting ties to the core. There is currently no generally accepted, globally consistent definition of exactly what constitutes a metropolitan area, thus making comparisons between cities in different countries especially difficult.^[1]

One attempt at arriving at a consistently defined metropolitan area concept is the study by Richard Forstall, Richard Greene, and James Pick. The basic principles of their definition involve delineating the urban area as the core, then adding surrounding communities that meet two criteria: (1) Less than 35% of the resident workforce must be engaged in agriculture or fishing; and (2) At least 20% of the working residents commute to the urban core.^[1] Based on their consistently defined metropolitan area criteria, they tabulate a list of the twenty largest metropolitan areas in 2003.^[1][2] As population figures are interpreted and presented differently according to different methods of data collection, definitions and sources, these numbers should be viewed as approximate. Data from other sources may be equally valid but differ due to being measured according to different criteria or taken from different census years.

Rank	Metropolitan area	Country	Population	Area (km2)	Population Density (People/km2)
1	Tokyo	Japan	32,450,000	8,014	4,049
2	Seoul	South Korea	20,550,000	5,076	4,048
3	Mexico City[3]	Mexico	20,450,000	7,346	2,784
4	New York City[4]	United States	19,750,000	17,884	1,104
5	Mumbai	India	19,200,000	2,350	8,170
6	Jakarta	Indonesia	18,900,000	5,100	3,706
7	São Paulo	Brazil	18,850,000	8,479	2,223
8	Delhi	India	18,600,000	3,182	5,845
9	Osaka-Kobe-Kyoto	Japan	17,375,000	6,930	2,507
10	Shanghai	People's Republic of China	16,650,000	5,177	3,216
11	Metro Manila	Philippines	16,300,000	2,521	6,466
12	Hong Kong-Shenzhen[5]	People's Republic of China	15,800,000	3,051	5,179
13	Los Angeles	United States	15,250,000	10,780	1,415
14	Kolkata	India	15,100,000	1,785	8,459
15	Moscow	Russia	15,000,000	14,925	1,005
16	Greater Cairo	Egypt	14,450,000	1,600	9,031
17	Buenos Aires	Argentina	13,170,000	10,888	1,210
18	London	United Kingdom	12,875,000	11,391	1,130
19	Beijing	People's Republic of China	12,500,000	6,562	1,905
20	Karachi	Pakistan	11,800,000	1,100	10,727

[edit] References and notes

[edit] See also

• World's largest urban agglomerations
• List of urban areas by population
• List of cities proper by population
• Larger Urban Zone - for an attempt at a harmonized definition for certain EU cities

[edit] Lists of metropolitan areas by region

• Africa
• Americas
• Asia
• Europe

[edit] Lists of metropolitan areas by country or region

[edit] External links

• Geopolis
• demographia.com
• citypopulation.de
• World Gazetteer
• PopulationData.net: all 1M+ inhabitants Metropolitan Areas
• OECD Territorial Reviews - Competitive Cities in the Global Economy - has some definitions for OECD countries